1. Technical Field
The present invention relates to electronic circuits in general, and in particular, to level shifter circuits. Still more particularly, the present invention relates to a level shifter circuit having improved characteristics in low to high voltage conversion operations.
2. Description of the Related Art
Modern integrated circuit (IC) devices often have to interface with IC devices from previous technology generations. However, the complementary metal-oxide semiconductor (CMOS) voltage levels on IC devices from previous technology generations are usually different from those on IC devices from the current technology generation. Thus, in order to ensure proper interfacing between different CMOS voltage levels, modern IC devices must include output buffer circuits that are capable of driving voltages greater or less than the source voltage.
Generally speaking, an output buffer circuit includes a level shifter circuit that is coupled to a power supply having a voltage different from the source voltage. In response to the values of the input signals, the level shifter circuit uses a set of output drivers to provide output voltages accordingly. For example, an output buffer circuit that receives input signals ranging from 0 V to 0.7 V output is capable of providing output signals ranging from 0 V to 3.3 V, accordingly.
The present disclosure describes a level shifter circuit having improved characteristics in low to high voltage transition operations.
In accordance with a preferred embodiment of the present invention, a level shifter circuit includes a first level shifter circuit and a second level shifter circuit. The first level shifter circuit and the second level shifter circuit are substantially identical with each other. The second level shifter circuit is coupled to the first level shifter circuit via a couple of transistors to provide an output and a complementary output, respectively.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.